Shot up 100mg morphine, EXTREME headache 20min later, why?

a few days ago I shot up 100mg of morphine, I used the same needle I had used the day before. I always clean my arm, clean spoon, clean hands and ive never shared anything with anyone. I use a piece of a new cigarette filter to filter the morphine. about 20min later I expiernced an EXTREMELY PAINFUL headache. I went to the ER, it was gone within 45min, I threw up a few times and had a slight fever. a minor headache lasted through the next day. does anyone know what might have caused this?

It probably didn't dilute into your blood enough before it reached your brain. That's Mother Nature's way of saying you're doing something stupid.